Pertussis, or the more commonly known as Whooping Cough has ailed humans for centuries. Many epidemics have been tracked across the globe over the years, but with widespread vaccination programmes during the 1940s and 50s, the disease was almost completely eradicated. This begs the question, why are cases starting to rise again?

About pertussis 

What is pertussis?

Pertussis is a bacterial infection caused by Bordetella pertussis, causing an acute respiratory infection. It is highly contagious and can be dangerous in young children and babies who are not protected against the illness. 

Symptoms

At the beginning of the illness, after a person has become infected, within 7-10 days symptoms start to appear. Symptoms include: 

• Sneezing
• Nasal discharge 
• Mild cough
• Low-grade fever 

As the illness progresses, the symptoms worsen, and the characteristics of whooping cough start to present, including:

• Thick mucus expulsion 
• Vomiting 
• Intense coughing fits 
• Cough with a crowing or “whoop” sounds 

These typically present themselves after 2 weeks and can continue up to 3 months.¹

Treatment 

Depending on the severity of the illness, treatments vary. More mild cases such as those seen in adults will require antibiotics to combat infection.²

There are several at-home measures to consider such as:

• Get plenty of rest
• Drinking lots of fluids - which helps to avoid dehydration
• Taking over-the-counter painkillers such as paracetamol or ibuprofen 
• Eat blander foods - avoid spice, high-fat foods and caffeine and alcohol to prevent further vomiting 

More severe illness may require hospital treatment, as rare complications such as seizures, brain inflammation and death can occur.

Transmission

• Primarily transferred through droplets - coughing and sneezing
• Droplets containing bacteria enter the body either by direct contact with bodily fluids or by inhalation
• Bacterium attaches to the cilia within the lungs and release toxins to inflame the respiratory system 

Therefore, when outbreaks are on the rise, it is important to keep good hygiene practices at all times such as regular hand-washing and it is vital to have up-to-date vaccinations.

Vaccination programmes 

In the UK, there is a widespread vaccination programme given routinely to all children. The pertussis vaccine is involved in two sets of vaccines 

• The 6-in-1 vaccine - is given to babies at 8, 12 and 16 weeks of age 

This vaccine also contains protections for diphtheria, hepatitis B, Hib, polio and tetanus.

• The 4-in-1 booster - is given to children over 3 years old 

This vaccine also contains protections for diphtheria, polio and tetanus.³

To have the majority of the population vaccinated is vital to achieve herd immunity. 

Herd immunity 

What is herd immunity?

Herd Immunity is defined as the protection from infectious diseases that occurs in a community when a large population of that community is immune (either naturally or by vaccination). Through the majority of individuals being protected, it allows the non-immune, vulnerable individuals to have higher protection rates, as the likelihood of contact with the disease is decreased, leading to reduced spread.⁴

Many groups cannot receive vaccines, like those with compromised immune systems, allergies to the vaccines, infants and some of the elderly population.

How is immunity achieved?

The immunity obtained by an individual can occur in several ways.

Natural immunity 

1. Exposure to disease through infection followed by recovery
2. The natural immune response is triggered creating antibodies to fight off disease in the organism 
3. When re-infected, the body is equipped to trigger a quicker and more widespread immune response
4. Natural immunity can take several weeks but a second infection response can occur in days 

Acquired immunity

1. Similar to natural immunity, the organism needs to become infected with the disease, except here it is introduced artificially as a vaccine 
2. The vaccine contains weakened bacteria to trigger antibody production
3. This method removes the risk of severe infection compared to natural immunity 
4. It protects vulnerable groups unable to fight off diseases naturally 

Passive immunity 

1. Occurs when antibodies are transferred from one individual to another 
2. Occurs during pregnancy from the mother to the baby
3. Vital for immunization to be completed in pregnancy
4. Provides immediate protection but wears off several weeks postpartum⁵

The threshold of when herd immunity is achieved varies by disease. The more infectious the disease, the higher the percentage of the population that needs to be immune. 

The biggest issue in maintaining herd immunity is the rate of vaccinations. In recent years, vaccine adherence has reduced, with most vaccination uptake below the 95% herd immunity goal.⁶

With faltering commitment and changing opinions of vaccinations, herd immunity rates are dropping, compromising protection for entire populations. 

Pertussis and herd immunity 

Impact of outbreaks 

Reported cases in England from January to March 2024 were almost 3 times higher than the entirety of the previous year, with a total of 2793 cases spanning the 3 months, including 5 infant deaths.⁷ Higher cases of a highly transmissible disease are always concerning, as higher incidence gives a higher risk of infection to vulnerable groups, due to the collapse of herd immunity. 

Role of vaccinations

Vaccinations can aid in reducing the spread of infections, by reducing the potential contraction of a disease and transmission to others, creating herd immunity.

One of the biggest challenges NHS England has reported is vaccination coverage in pregnant women, which has fallen significantly for the pertussis vaccine over recent years. Pre-pandemic vaccine uptake was approximately 64%, now dropping to 59% in late 2023 and early 2024.⁸

The vaccine is recommended between 16 and 32 weeks gestation to give unborn babies passive immunity against the disease. This is vital, as the most vulnerable group to whooping cough are infants under 3 months, those who do not qualify for their first 6-in-1 immunization and are therefore unprotected.

The vaccine for pregnant women has shown to reduce rates of pertussis, and morbidity in infants under 3 months and there is no evidence to suggest this immunisation is harmful to the baby or the mother.⁹

Similarly, rates of booster completion are on the decline. For the UK in particular, almost 100% of children receive at least 1 dose, but completion of all doses is just over 80%.¹⁰ Several doses are essential to obtain full, long-lasting immunity and to ensure herd immunity is high enough for community protection.

Challenges

Risk 

The aspect of risk is always to be considered when producing and releasing vaccinations widespread. Pertussis, its first controversy arose in the 1970s, after doctors claimed the vaccination caused encephalopathy. From then on, public opinion became negative and vaccine uptake reduced.¹¹

After years of declining vaccination rates, the pertussis rates and fatalities rose again. Several studies have established that there had been between 1 and 10 cases of encephalopathy per million immunisations, but no studies could confirm that these were related.¹²

No vaccination or medicine that comes without risk. However, the risk of catching pertussis and the potentially fatal outcomes greatly outweigh the risk of the vaccine itself. 

Misinformation

Skeptical views of vaccinations have plagued the nations with numerous fake news or incoherent articles on vaccine studies. This contributes to outbreaks, which have been seen across the UK, from measles to polio and increasing cases of pertussis.

The anti-vaccine movement has been apparent for many years, most notably spiking during the late 90’s, when a study suggesting a link between autism and the MMR vaccine was published. Although no causal link had been found in this very small study (12 children), this statement that the MMR vaccine was dangerous had reached media outlets causing international outcry. This led to distrust in health professionals, and reduction in vaccination uptake, an issue that still lingers to this day.¹³ 

As a result, cases rose, and herd immunity could not be maintained.

With distrust and lack of compliance with public health campaigns, outbreaks and even pandemics can occur.

Spotting misinformation

Understanding complex concepts and areas that are uncertain to you makes it difficult to distinguish what is fact and what is fiction, especially in a digital media world. Cancer Research UK has some helpful tips on their website here.

Strategies 

Strengthening vaccine programmes

• Widely accessible immunisation appointments or on-site vaccinations¹⁴
• Vaccines offered to mothers/fathers and caregivers of newborns - called the cocooning strategy¹⁵ 
• Consistent booster programmes for adolescents 

Education and awareness 

• Explanation of vaccines, all risks involved, positive and negative - gives patients an informed choice 
• Recommendation of vaccines for healthcare or childcare workers
• Public health campaigns - minimises the spread, encourages vaccination, contributes to herd immunity¹⁶ 

Surveillance and response 

• Collection of data from physicians to be given to reporting or research bodies 
• Early detection - avoidance of outbreaks 
• Contact tracing for potentially infected individuals
• Strategies for worst case scenario and appropriate intervention
• Guides public health policy 

Summary

To summarise, understanding the changing trends of vaccine uptake and the impact of herd immunity is essential to implementing control measures and protecting public health. With strategies for improvement in place and addressing the challenges for vaccine coverage, the incidence of pertussis can be decreased through the protection of herd immunity, which is possible, with public compliance.